Interface ProcessingInstruction

The ProcessingInstruction interface represents a "processing
instruction", used in XML as a way to keep processor-specific information
in the text of the document.

No lexical check is done on the content of a processing instruction and
it is therefore possible to have the character sequence
"?>" in the content, which is illegal a processing
instruction per section 2.6 of [XML 1.0]. The
presence of this character sequence must generate a fatal error during
serialization.